Core-Shell Ceramic Grain Pores for Capacitor Insulation Reliability
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Solution Overview
Problem
The migration of oxygen defects from the dielectric layer to the interface between the internal electrode layers in laminated ceramic capacitors leads to increased leakage current and decreased insulation reliability.
Innovation Solution
Incorporating crystal grains with a core-shell structure in the ceramic layers, where the shell portion contains intra-shell pores, inhibits the migration of oxygen defects by providing voids that prevent their movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth elements are added to the dielectric layer to improve capacitance and high-temperature load life, then capacitance and high-temperature load life are improved, but oxygen defects occur in the dielectric layer which migrate to the internal electrode layer and increase leakage current
Solution Approach 1:
The patent introduces intra-shell pores within the shell portions of crystal grains in the dielectric layer. These pores act as trapping sites for oxygen defects, preventing their migration to the internal electrode layer interface. The porous structure within the crystal grains provides a pathway to capture and immobilize oxygen defects generated by rare earth element addition, thereby maintaining low leakage current while preserving improved capacitance and high-temperature load life.
Solution Approach 2:
The patent creates a composite crystal grain structure with core portions and shell portions containing intra-shell pores. This core-shell composite structure combines the beneficial effects of rare earth element doping (improved capacitance and thermal stability) with the defect-trapping capability of porous shell regions, effectively resolving the contradiction between performance enhancement and defect generation.
2Reliability
If oxygen defects accumulate at the interface between the dielectric layer and internal electrode layer, then leakage current increases, but insulation reliability decreases
Solution Approach 1:
The intra-shell pores within the crystal grain shell portions serve as intermediary trapping sites between the dielectric layer interior and the internal electrode layer interface. Oxygen defects are captured in these intermediate pore regions, preventing their direct migration to the harmful interface location. This intermediary mechanism effectively reduces leakage current while maintaining insulation reliability.
3Reliability
If the dielectric layer contains crystal grains without intra-shell pores, then manufacturing is simpler, but oxygen defects migrate freely causing decreased insulation reliability
Solution Approach 1:
The patent incorporates intra-shell pores within crystal grain shell portions to create a porous internal structure that traps oxygen defects. This porous structure, while adding complexity to the crystal grain morphology, provides essential defect management functionality that cannot be achieved with dense, non-porous structures, thereby improving insulation reliability.
Data Source
AI summary
One object is to improve the insulation reliability of a laminated ceramic capacitor. The body of a laminated ceramic capacitor according to one embodiment includes a first internal electrode layer, a second internal electrode layer, and a ceramic layer. The ceramic layer is disposed between the first internal electrode layer and the second internal electrode layer and contains crystal grains of ceramic material. The crystal grains each include a core portion and a shell portion covering the core portion. The shell portion includes one or more intra-shell pores.